Interrupting high tension direct current is a difficult problem.
An object of the invention is to provide apparatus capable of solving this problem reliably and cheaply.
The principle on which the present invention is based comprises the combination of first means known per se for limiting the value of the current to be interrupted and then enabling second means, also known per se to be applied to finally interrupt the residual current.
The first means are constituted, for example, by those described in Document FR-A-2 073 731, and comprise a superconducting winding for limiting a fault current to a nominal current value by the winding switching to the normal conductivity state. The Document mentions that the residual current is interrupted by a power circuit breaker. This is easy with alternating current, but very difficult with direct current.
That is why, the present invention proposes associating said first means with second means such as those described in the document IEEE Transactions on Power Apparatus and Systems, PIS 104 1985, September 9 "Development of a 500 kV airblast HVDC circuit breaker" by B. Bachman, G. Mauthe, E. Ruoss, and H.P. Lips. These second means comprise a series-resonant circuit capable of injecting an oscillating current into the circuit, thereby generating zero crossings in the current to be interrupted. The novel and original combination of the invention makes it possible to interrupt currents of several thousand amps at tensions of about 100 kV.